3com 4210 PWR 9-Port 3CR17341-91-ME ユーザーズマニュアル

C

HAPTER

 23: ARP C

ONFIGURATION

In an Ethernet, the MAC addresses of two hosts must be available for the two 
hosts to communicate with each other. Each host in an Ethernet maintains an ARP 
table, where the latest used IP address-to-MAC address mapping entries are 
stored. The Switch 4210 provides the display arp command to display the 
information about ARP mapping entries.

ARP entries in the Switch 4210 can either be static entries or dynamic entries, as 
described in Table 212.

Table 210   Description of the ARP packet fields

Hardware Type 

Type of the hardware interface. Refer to 
Table 211 for the information about the field 
values. 

Protocol type 

Type of protocol address to be mapped. 
0x0800 indicates an IP address. 

Length of hardware address 

Hardware address length (in bytes) 

Length of protocol address 

Protocol address length (in bytes) 

Operator 

Indicates the type of a data packets, which 
can be:

■

1: ARP request packets

■

2: ARP reply packets

■

3: RARP request packets

■

4: RARP reply packets 

Hardware address of the sender 

Hardware address of the sender 

IP address of the sender 

IP address of the sender 

Hardware address of the receiver 

■

For an ARP request packet, this field is null.

■

For an ARP reply packet, this field carries 
the hardware address of the receiver. 

IP address of the receiver 

IP address of the receiver

Table 211   Description of the values of the hardware type field

1 

Ethernet 

2 

Experimental Ethernet 

3 

X.25 

4 

Proteon ProNET (Token Ring) 

5 

Chaos 

6 

IEEE802.X 

7 

ARC network

Table 212   ARP entries

Static ARP entry 

Manually configured 

Manual maintenance 

Dynamic ARP entry 

Dynamically generated 

ARP entries of this type age 
with time. The aging period is 
set by the ARP aging timer.